Leonardo Cesar Kammer

Trajectory synchronization and negotiation in Trajectory Based Operations

Trajectory Based Operations (TBO) is a key component of both the US Next Generation Air Transport System (NextGen) and Europes Single European Sky ATM Research (SESAR). There is a significant amount of effort underway in both programs to advance this concept. Trajectory Synchronization and Negotiation are key required capabilities in both the NextGen and SESAR TBO concepts, and they provide the framework to improve the efficiency of airspace operations. In recognition of the importance of TBO, General Electric and Lockheed Martin have created a Joint Strategic Research Initiative (JSRI), which aims to generate technologies that accelerate adoption of TBO. This paper explores various trajectory synchronization and negotiation concepts, including existing gaps and shortfalls. This paper also presents the JSRI simulation and evaluation environment being developed, which embeds trajectory synchronization and negotiation concepts, and has the potential to address existing gaps and shortfalls.

Technical communique: Stability assessment for cautious iterative controller tuning

This document presents a model-free test for stability assessment in iterative controller tuning. The information required for the test is obtained from the currently available stable closed-loop system, and does not include a model of the plant. All controllers that satisfy the test are guaranteed to stabilize the actual plant.

Stability assessment for cautious iterative controller tuning

This document presents a model-free test for stability assessment in iterative controller tuning. The information required for the test is obtained from the currently available stable closed-loop system, and does not include a model of the plant. All controllers that satisfy the test are guaranteed to stabilize the actual plant.

Active Combustion Control by Fuel Forcing at Non-Coherent Frequencies

One impediment to substantially further the reductions in NOx emissions for aviation gas turbine engines is thermal-acoustic instabilities, also referred to as combustion dynamics. Dynamics arise due to the coupling of heat and pressure fluctuations in such systems. Numerous passive and semi-active control schemes, including performance de-rating and fuel staging, have been developed for land-based gas turbine engines. However, many of these schemes are not well suited to aviation engines, as a result of their weight and bulk. Observations of several combustors operating on either gaseous or liquid fuels show that the dominant dynamic frequencies have a special relation to specific non-coherent lower frequencies. Experiments show that combinations of two of these non-coherent frequencies form the dominant tones of the combustor. As part of NASA’s intelligent engines program, active combustion control is used to mitigate dynamics, as the combustor’s bulk fuel-air ratio (FAR) is made leaner in an effort to reduce NOx emissions by about 85% below the Committee on Aviation Environmental Protection (CAEP) 6 limit. In the feedback control scheme suggested in this paper, a small percentage of the overall fuel flow is pulsed at a given non-coherent frequency and with varying amplitude. The effectiveness of the dynamics reduction approach has been demonstrated via preliminary open loop control tests on a liquid-fuelled partially premixed high-pressure combustion test rig at GE Aviation in Evendale, Ohio.Copyright